Not generating model-specific code for a processor that doesn't match your CPUID table is hardly what I'd call "sabotaging."
If you want more, use a different compiler, period. $VENDOR spends money on their compiler to support their chips, not to appease every whining, butt-hurt user on the Interwebz that thinks $BIGCO owes them something on a competing chip.
If your CPU lies about its feature support, there are far, far, far bigger problems for the end user than whether a binary is optimal or not.
In this case, the optimal thing to do was not to use these instructions despite the processors claiming support.
Of course. This is obvious, if you had any idea about what you were talking about.
" I would only enable specific optimizations when I could guarantee the output would be optimal or a given model."
You can do that with compiler flags, ever heard of them?
They're already doing that by checking whether it says it's a genuine Intel. If you can't trust it when it says that it supports a feature, why trust it when it reports a manufacturer?